/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    UnivariateNumericBinarySplit.java
 *    Copyright (C) 2013 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.classifiers.trees.ht;

import java.io.Serializable;

import weka.core.Attribute;
import weka.core.Instance;

/**
 * A binary split based on a single numeric attribute
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @author Mark Hall (mhall{[at]}pentaho{[dot]}com)
 * @version $Revision$
 */
public class UnivariateNumericBinarySplit extends Split implements Serializable {

    /**
     * For serialization
     */
    private static final long serialVersionUID = -7392204582942741097L;

    /** The split point */
    protected double m_splitPoint;

    /**
     * Constructor
     * 
     * @param attName    the name of the attribute to split on
     * @param splitPoint the split point
     */
    public UnivariateNumericBinarySplit(String attName, double splitPoint) {
        m_splitAttNames.add(attName);
        m_splitPoint = splitPoint;
    }

    @Override
    public String branchForInstance(Instance inst) {

        Attribute att = inst.dataset().attribute(m_splitAttNames.get(0));
        if (att == null || inst.isMissing(att)) {
            // TODO -------------
            return null;
        }

        if (inst.value(att) <= m_splitPoint) {
            return "left";
        }

        return "right";
    }

    @Override
    public String conditionForBranch(String branch) {
        String result = m_splitAttNames.get(0);

        if (branch.equalsIgnoreCase("left")) {
            result += " <= ";
        } else {
            result += " > ";
        }

        result += String.format("%-9.3f", m_splitPoint);

        return result;
    }
}
